W.Green, G.Swanborough The Complete Book of Fighters

SPAD S.XI France

The basic SPAD S.XI was intended by Louis Bechereau as a two-seat fighter. When the prototype appeared in September 1916, it was clearly descended from the S.VII, but it had conventional two-bay interplane bracing for its longer wings, which were staggered and featured sweepback. Powered by a 220 hp Hispano-Suiza 8Bc eight-cylinder water-cooled Vee-type engine, the S.XI was found to possess extremely sensitive handling qualities and was deemed unsuited for the fighter role. It was adopted as a Corps d'Armee reconnaissance aircraft, however, entering production as the S.XI A2. It proved a dismal failure in service, largely for reasons unassociated with the basic design, yet 1,000 examples were produced. In an attempt to create a two-seat night fighter, one of these was experimentally fitted with a frontal searchlight as the S.XI Cn2. The mounting of the searchlight ahead of the propeller clearly drew on SPAD’s earlier experience in mounting the forward nacelle of the Type A series. It may be assumed that the S.XI Cn2 proved unsuccessful under test as only one example was completed. The following data are for the S.XI A2, but those for the Cn2 version can be assumed to have been similar.

G.Swanborough, P.Bowers United States Military Aircraft Since 1909 (Putnam)

SPAD 11A-2 and 16 A-2

The Spad 11 and 16 were fast two-seat reconnaissance types developed from the Spad VII. Retaining the same short nose of the single seater made it necessary to sweep back the wings of the two seater for balance purposes. Thirty-five 11A-2s were procured, and have erroneously been referred to ever since as Spad 112 because the caption on the most-used photo released by the Office of Public Information in World War I inadvertently left the letter A and the dash out of the designation 11 A-2. The Model 16, of which there were six in the A.E.F. was an identical airframe with a 250-h.p. direct drive Lorraine engine.

Журнал Flight

Flight, May 16, 1918.

THE SPAD TWO-SEATER.200 H.P. HISPANO-SUIZA ENGINE.

THE following particulars and illustrations, apparently from an official report on the Spad two-seater, are published in Flugsport of April 10th :- The Spad two-seater, which is shown in the accompanying illustrations, is marked B 6006, and is built under licence in July, 1917, by the Aircraft Works of Ad. Bernard in La Courneuve (Seine). In general design and in constructional details it resembles the single-seaters, but does not have the divided inner interplane struts usually found on these. It is built as an ordinary two-strutter. The spars of the lower wings are braced to the under-carriage from the point of attachment of the inner pair of struts. The upper wing, which runs right through, has a span of 11.22 metres, and a chord of 1.53 metres, while the lower wing has a span of 10.90 metres and a chord of 1.43 metres. The gap is 1.335 metres and the stagger 0.4 metre. There is no dihedral angle, but both upper and lower wings are swept back, the angle being 174°. In order to give a better view, the lower wings have been cut away near the body, and the upper wing has a cut-out portion in the centre. The two spars are placed closer together than those of the lower wing, and the interplane struts converge somewhat upwards. The angle of incidence of the upper plane is 2.8° in the centre, and 2.5° at the tip, while the lower plane has a uniform angle of 1.5°. The lift wires are in duplicate, and in order to reduce head resistance, the space between them is filled up with strips of wood. The landing wires are single. A drift cable runs, from the junction of the inner interplane strut to the upper front spar, to the point of attachment of the front under-carriage strut. The interplane struts, which are of streamline section, are made of wood. Their fittings are attached to a steel tube carried inside the strut. The spacing of the ribs is 190 mm. in the top wing and 175 mm. in the lower wing. Between the ribs there are false ribs on the upper surface running from leading edge to front spar. The fabric is tacked to some more strongly constructed ribs, and is, in addition, stitched to ribs and to the wire forming the trailing edge. On the under surface, near the trailing edge, there are eyelets which serve to equalise the pressure and to drain any moisture out of the wing. Wing and body covering are painted a yellowish white. Non-balanced ailerons are hinged to false spars in the upper plane. They are operated by means of pull and push rods which rest in the lower plane behind the rear spars, and the movement of which is transmitted through cranks at the lower ends of the outer struts, to vertical struts pivotted to the lower surface of the aileron. The body, which is of the usual construction, with four longerons, is rounded off top and bottom by formers and stringers. The longerons have a rectangular section, while the vertical and horizontal body struts are spindled out to an I section, and are reinforced by plywood. A trap-door in the floor behind the observer's cockpit provides access to the interior of the body. The stabilising and control surfaces are of the usual Spad type. The tail plane, which runs right across the body, and has both sides cambered, is attached to the upper longeron at an angle of incidence of 0°. To its trailing edge, the divided elevator is hinged by means of a steel tube. In order to reduce resistance, the cranks are placed in the centre inside the body and vertical fin. The machine is provided with dual control. For operating the ailerons, the movement of the control shaft is transmitted by means of a lever, to a rocker supported in a partition between pilot's and observer's cockpits. The rods - which rest in the bottom wing - engage with a downward projection of this rocker. The observer's control lever is in the form of a telescopic tube, whose upper part is forced upwards by a spiral spring, or pressed down when not in use, and held in position by a bayonet joint. When extended, its length measured from the pivotting point is 53 centimetres, and when telescoped it measures 36 centimetres. The rudder bar in the observer's cockpit can be covered over with detachable covers, to guard against accidental use. The V form under-carriage struts are made up of several layers of wood glued together, and the whole covered with fabric. Diagonal bracing is employed in both front and rear bays. The two stub axles rest between two cross tubes covered with fabric, and move in slots in the struts. The travel is 125 mm. The VEE type Hispano-Suiza engine, which develops about 200 h.p. at 2,000 r.p.m., rests on engine bearers which are connected up to the body longerons by means of transverse supports of three-ply wood, and angle pieces pressed out of aluminium. The two-bladed air screw is geared down, by means of gearing incorporated with the engine in the ratio 4:3. The exhaust gases are carried away by collectors on each side of the body extending to behind the pilot's seat. A pressure petrol tank with a capacity of 140 litres forms the pilot's seat, while a gravity tank holding 10 litres is mounted in the upper wing, between the spars. The oil tank, which holds 15 litres, rests on the floor of the body behind the engine. The bottom of the oil tank has pressed on it ribs for cooling the oil. The fuel capacity is sufficient for a flight of about 2 hours' duration. The radiator, which is provided with shutters, forms the nose of the fuselage. A reservoir connected with the radiator is built into the upper wing in front of the front spar. Any steam or excess water is carried off underneath the body by means of an overflow and a pipe. The pilot's seat, which as in all Spad aeroplanes is kept very narrow, is separated from the engine by a linen curtain. In front of it is a wind screen divided into three parts and framed in aluminium. Of instruments, &c, there are as follows: On the right: The starter and the hand operated air pump. In the centre: Two switches, one three-way cock for pressure tank and connecting up with cither hand or motor air pump, one three-way cock handle for turning on or off the petrol from tank to carburettor, one tap for turning the motor air pump off from the pressure tank, one manometer, and the revs, indicator. On the left: The gas lever, lever for regulating the mixture, and lever for operating the radiator shutters. There is no provision made for advancing or retarding the magneto. The instruments are to a certain extent badly arranged. Thus the revs, indicator is placed with its dial horizontal and so that the pilot sees the figures upside down. In the observer's seat are, in addition to the dual controls, two switches, one gas lever, and one lever for regulating the mixture, so that, apart from the petrol controls, the observer can look after the engine. Wireless installation is not fitted, although antennae wires are provided in the body. The armament consists of a fixed Vickers machine gun mounted above the body, for the pilot. The gun is operated by a push-rod from the right hand cam shaft. The trigger is on the control lever. The observer is armed with two Lewis machine guns coupled together. Six ammunition drums can be carried in the observer's cockpit, suitable brackets being provided. The weight of the machine empty, but including the cooling water, was ascertained to be 765 kg. A notice on the rudder gives they useful load (poids utile) as 255 kg. and the fuel weight (poids combustible) as 120 kg. This gives a total weight of 1,140 kg., so that the weight per sq. m. (the area is 29.8 sq. m.) is 1140/298 = 38.5 kg., and the weight per h.p. is 1140/200 = 5.7 kg.

The two-seat Spad XI was conceived as a reconnaissance-bomber but following its introduction in 1917 was not a great success. Nevertheless, it was delivered in large numbers and continued in use until mid 1918.[Janes] Side View of a British two-seater Spad XI, captured by the germans. Developed from the Spad VII, it achieved 175 km.p.h. on a 235 h.p. Hispano-Suiza engine.

KING ALBERT OF BELGIUM REVIEWS HIS ARMY FROM AN AEROPLANE. - The Royal plane, taken from another plane above it. Below may be seen the Belgian lines, roads, &c., and at the top of the picture the inundations.